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<p>In Einstein notation, the usual element reference  for the -th row and -th column of matrix  becomes . We can then write the following operations in Einstein notation as follows.</p>

<p><big> Inner product </big></p>
<p>The <a href="page.php?w=inner_product">inner product</a> of two vectors is the sum of the products of their corresponding components, with the indices of one vector lowered (see ):</p>

<p>In the case of an <a href="page.php?w=orthonormal_basis">orthonormal basis</a>, we have , and the expression simplifies to:</p>

<p><big> Vector cross product </big></p><p>
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